The correct option is C 10.6
2NaHCO3Δ−→Na2CO3+H2O+CO2
1.12 L CO2 at STP corresponds to 1.12L22.4L/mol=0.05 moles.
0.05 moles of CO2 will come from 2×0.05=0.1 mole of NaHCO3.
The molar mass of NaHCO3 is 84 g/mol. Mass of 0.1 moles of NaHCO3=84×0.1=8.4g
Mass of Na2CO3=19−8.4=10.6g